1. Field of the Invention
The present invention relates to a method of manufacturing an active material, an active material, an electrode using the active material, and a lithium-ion secondary battery equipped with the electrode.
2. Related Background Art
LiFePO4 has been under study as one of positive electrode active materials for lithium-ion secondary batteries from the viewpoint of safety during operations of the batteries. However, LiFePO4 is inferior to LiCoO2, for example, in terms of electronic and ionic conductivities. Therefore, lithium-ion secondary batteries using LiFePO4 as their positive electrode active material have been hard to yield a sufficient discharge capacity at a high discharge current density.
Japanese Translated International Patent Application Laid-Open No. 2005-530676 discloses a method of making a powder of LiFePO4 having a surface covered with carbon. According to the method described in the Patent Document: the above-mentioned electrode active material is manufactured by mixing a solution in which a polyhydric alcohol and a polycarboxylic acid are mixed, an Li salt, an Fe salt, and a phosphate; polymerizing the polyhydric alcohol and polycarboxylic acid by dehydration condensation; and heating thus obtained polymer.